1. Field of the Invention
The present invention relates to a clog detecting device that indicates clogging of a dust collecting filter in a dust collector for collecting dust laden fluid such as dust laden oil mist (including oil smoke) generated in a machine tool or the like in a shop.
2. Description of Related Art
In a shop doing machine work, machine tools generate dust laden oil mist or the like. If left untreated, the oil mist not only makes working environment of the shop worse by causing bad odor in the shop, intrusion of the dust laden fluid into equipment and its control panels and dirt of walls, but also makes the floor of the shop slippery, which may cause fall of operators.
For this reason the dust laden fluid is required to be collected by a dust collector steadily and efficiently. To this end, such equipment as machine tools generating dust laden oil mist are usually provided with a dust collector that collects dust laden fluid with a dust collecting filter.
As the dust collecting filter collects the dust laden fluid, it is clogged due to collected dust laden fluid, which turns down collection efficiency of the filter and lets uncollected dust laden fluid released in the shop, thus making the working environment worse as described above.
This must be solved by frequent maintenance and inspection of the dust collecting filters, but it is difficult for a busy shop worker to watch the filters all of the time and clean or replace the filters as soon as they are clogged. JP 5-285325 A and so on discloses a device for monitoring clogging of a dust collecting filter in order to cope with such circumstances. The device includes in a suction chamber a pressure sensor for detecting a suction pressure of a blower for dust collection such that a detection signal is fed and clogging of a filter is announced when the suction pressure in the suction chamber surpasses a predetermined pressure.
However, in addition to electric sensing by the pressure sensor, the above conventional clog monitoring device also uses a temperature sensor for monitoring clogging of the filter. Since the device monitors clogging by means of a temperature signal as well as a pressure detection signal, the device has a complicated structure with the sensors and their detection circuits, and costs a lot of money for manufacturing. Further, the device requires maintenance and inspection for the sensors and detection circuits.
There is also known a clog indicating device including a damper pivotally supported at an exhaust port of the dust collector, an index needle mounted on a rotary shaft of the damper such that clogging of a filter is indicated by the index needle when a rotation angle of the damper is reduced.
However, although the index needle is mounted on a lateral of the exhaust port of the dust collector, the needle is very thin and is not easily viewable in a large shop, therefore it is not easy for operators to notice of clogging.